Measurements of the Thermal Conductivity of Pyrolitic Graphite Substrates for use in SCT Modules

We describe direct measurements of the thermal conductivity of pyroliticgraphite (pg and tpg) proposed for removing heat from the Atlas SCT modules.For tpg the crucial conductivity (parallel to the lamina plane) is in excessof 1700W/m-K at room temperature with an appreciable negative temperaturecoefficient and is radiation hard. Measurements of the conductivity perpendicularto the lamina plane suggest that a thin polyimide coating, if required, wouldnot seriously affect its performance.